Photo/Illutration Defense Ministry officials explain errors found in the ministry's report on candidate sites for the Aegis Ashore missile defense system to the Akita prefectural assembly on June 5. (The Asahi Shimbun)

Incredible errors in the Defense Ministry’s report on where a U.S.-made Aegis Ashore missile defense system should be deployed seriously undermine the credibility of the research conducted to select candidate sites.

The report concluded that the Ground Self-Defense Force’s Araya exercise area in Akita, capital of northern Akita Prefecture, was the only suitable site in eastern Japan for the land-based variant of the Aegis defense system against ballistic and cruise missiles.

But multiple errors have been discovered in vital data on which the report was based.

In response to requests from local communities around the Araya exercise area, the ministry studied 19 state-owned plots of land in Aomori, Akita and Yamagata prefectures to assess their appropriateness for hosting the expensive defense system.

The report claimed none of these sites was suitable for the project. Nine of them were ruled out as candidates because they were surrounded by mountains that would block radar pulses for detecting and tracking incoming missiles.

As it turned out, however, the angles of elevation of the peaks of those surrounding mountains given in the report were all larger than the actual figures.

In the case of state-owned land in Oga, Akita Prefecture, for example, the report said the angle of elevation of the mountain west of the site was 15 degrees. But it was actually 4 degrees.

The ministry apologized and announced corrections in the data, saying the errors were caused by using wrong scales for the calculations.

Speaking at a Lower House Security Committee on June 6, Defense Minister Takeshi Iwaya pledged to take every possible measure to “ensure there will never be such errors again.”

But the ministry has not changed the report’s conclusion that the Araya exercise area is the only realistic candidate site. It has ruled out five of the nine sites by saying the mountains can still block the radar beam, and pointed to underdeveloped infrastructure for the remaining four.

It is hard to believe the ministry’s claim that they were simple errors in calculation. If that is true, the ministry should be accused of gross incompetence.

It appears more likely that the ministry had already decided on the Araya site for the deployment and was only interested in reinforcing the case when it carried out the research.

The local communities are highly unlikely to accept the plan despite these revelations. The ministry should make a sweeping review of its research.

The errors were exposed by Akita Sakigake Shimpo, a local newspaper. Had it not been for the daily’s report, the ministry would have stepped up its pressure on the local communities to accept the deployment plan.

The report says the Aegis Ashore battery would not cause any harmful electromagnetic effects on human body, medical equipment or aircraft within surrounding areas, citing various measurement data.

Given the discovery of sloppy data processing, however, this claim cannot be taken at face value, and it does little to ease anxieties among local residents.

In a separate report, the ministry has cited a GSDF exercise area in Yamaguchi Prefecture as the other candidate site for the missile defense system in western Japan and explained the conclusion to the local communities. This report should also be re-examined carefully.

In stressing the need to introduce the pair of Aegis Ashore systems, the reports say the deployment of the systems to the two sites in Akita and Yamaguchi prefectures would make it possible to protect all of Japan 24 hours a day. But they offer no convincing information to support this claim.

The government should rethink its plan to deploy the two Aegis Ashore batteries from the viewpoint of whether these expensive weapons systems would really enhance Japan’s security.

--The Asahi Shimbun, June 7